It may have begun with a sneeze at Disneyland.
The measles outbreak traced back to the Anaheim theme park could show us how far a sneeze can travel. Health officials in California and the nation are scrambling to contain the outbreak of this extremely contagious disease, which can lead to hospitalization and death.
The virus spreads through coughing and sneezing. An infected person can sneeze, walk away, and the virus can continue to live in the air for two hours, according to the U.S. Centers for Disease Control and Prevention. And there is rarely unoccupied airspace in Disneyland, where 16.2 million people visited in 2013.
The happiest -- and at times one of the most crowded -- places on Earth is "ideal" as the launching site for a widespread measles outbreak.
"This is the ideal scenario," said pediatric infectious diseases expert James Cherry. People go to Disneyland "from all different counties and all different states."
Then some hop a plane to go home before being diagnosed with measles.
Health officials are tracking hundreds of people who could have been in contact with the two infected parkgoers in visits between Dec. 17 and 20. They are identifying spots where contagious people have visited -- such as a Ralphs in San Clemente, the Morongo casino in Cabazon, a Laguna Beach Starbucks.
The California Department of Public Health has asked residents to be on guard.